Congenital defects in newborn foals of mares treated for equine protozoal myeloencephalitis during pregnancy.

The research discusses the observed congenital defects in foals born to mares that were treated for equine protozoal myeloencephalitis during their pregnancy. It suggests a link between the oral administration of certain medications to pregnant mares (like sulfonamides and 2,4-diaminopyrimidines alongside folic acid) and the birth of weak foals with skin and internal organ malformations.

Research Background

• The study involved three newborn foals born to mares being treated for equine protozoal myeloencephalitis – a neurological disease found in horses caused by a protozoal infection.
• These mares received oral medication consisting of sulfonamides such as sulfadiazine or sulfamethoxazole-trimethoprim, pyrimethamine, folic acid, and vitamin E.

Observations and Findings

• The foals were found to be weak, unable to stand, and exhibited skin abnormalities such as a thin wooly coat.
• From a blood test, these foals were determined to be anemic, leukopenic, azotemic, hyponatremic, and hyperkalemic – all conditions suggesting poor health and possible organ failure.
• The foals had lower serum folate concentrations, a significant vitamine necessary for the synthesis and repair of DNA and RNA, in comparison to the reported levels for healthy mare foals. The mares themselves also had low serum folate concentrations.
• Treatments attempted for the foals were unsuccessful, and post-mortem examinations revealed lobulated kidneys with thin cortices and pale medulla, small spleen and thymus, and histological examination showed marked epidermal necrosis without inflammatory cells, thin renal cortices, renal tubular nephrosis, lymphoid aplasia, and bone marrow aplasia and hypoplasia.

Suggested Conclusions of the Study

• The clinical and post-mortem observations from the study led to the conclusion that the congenital defects in newborn foals were possibly due to the administration of specific medications to mares during their pregnancy.
• The medications involved were sulfadiazine or sulfamethoxazole-trimethoprim, pyrimethamine combined with folic acid, which are typically used to treat equine protozoal myeloencephalitis in mares.

Implications of the Research

• This research suggests that there might be a need to re-evaluate the safety of the current medication protocol for equine protozoal myeloencephalitis in pregnant mares.
• More in-depth studies may need to be undertaken to accurately identify the cause and possibly prevent such occurrences.